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Biomedical subjects

P Poppe

Publications and source records attributed to P Poppe.

14 recordsLinked to original sources
PubMed1999

The role of trabecular demineralized bone in combination with perichondrium in the generation of cartilage grafts.

The use of a composite graft of bovine trabecular demineralized bone matrix (DBM) and perichondrium has been found a reliable method for in vivo generation of cartilage. In the present study, the mechanism whereby this commercially available matrix increases cartilage formation was investigated. First, the time course of cartilage formation in vivo, in the combined implant of perichondrium and DBM in the rabbit ear was studied, with special focus on tissue reactions to DBM. DBM was colonized by macrophages from day 3 post-operatively, reaching a maximum after 2 weeks. Only a minimal number of neutrophils was found. After 3 weeks the DBM appeared to be resorbed. In the first week the DBM was invaded with chondroblasts, and chondrogenesis occurred between the first and second week of implantation. After 3 weeks, the initially formed islets of cartilage had fused. Next, the chondrogenic capacity of DBM itself was investigated by implantation of DBM without perichondrium. This never resulted in cartilage formation. Immunohistochemistry showed only a faint staining of the DBM for growth factors. This indicates a minimal chondrogenic effect of DBM alone and the requirement of perichondrium as cell provider. In order to define the conditions which cause chondrogenesis in composites of perichondrium and DBM, a series of in vitro culture experiments was performed in which the in vivo situation was mimicked step by step. The basic condition was perichondrium cultured in medium with 10% FCS. In this condition, cartilage formation was variable. Because in the in vivo situation both DBM and macrophages can release growth factors, the effect of IGF1, TGFbeta2 or OP1 added to the culture medium was tested. Neither the incidence nor the amount of cartilage formation was stimulated by addition of growth factors. Perichondrium wrapped around DBM in vitro gave cartilage formation in the perichondrium but the incidence and amount were not significantly stimulated compared to cultures of perichondrium without DBM. However, cartilage-like cells were found in the DBM suggesting an effect of DBM on perichondrium-derived cells. Finally, macrophages and/or blood were added to the composite DBM-perichondrium to mimic the in vivo situation as close as possible. However, no effect of this treatment was found. In conclusion, this study indicates that DBM itself has few chondrogenic qualities but functions merely as a spacer for cell ingrowth. The fast resorption of DBM by macrophages in vivo seems of importance for the cartilage forming process, but in vitro the presence of macrophages (in combination with blood) could not enhance chondrogenesis.

Animals↗
PubMed1994

Are histamine H1 receptors involved in ischaemia/reperfusion injury in rat heart?

During ischaemia, there was no apparent change in malondialdehyde (MDA) content in rat myocardium. However, reoxygenation resulted in a significant increase in MDA content. The changes evoked by ischaemia and reoxygenation were significantly attenuated by addition of fenistil (histamine H1 receptor antagonist). Enzymatic antioxidant systems were not significantly modified in the different periods of ischaemia and after 30 min of reoxygenation. It is suggested, that maintenance of an adequate endogenous antioxidant reserve during ischaemia may be important in recovery upon reoxygenation.

Animals↗
PubMed1989

Partial section of the corpus callosum: focal signs and their recovery.

A 30-year-old woman underwent surgical partial callosotomy (posterior half) for removal of an arteriovenous malformation. The patient submitted to neuropsychological evaluation before and after surgery for a period of 8 months. There was transient dysfunction attributable to disconnection of parietal, temporal, and occipital connections. Because the symptoms disappeared over time, we conclude that the transcallosal surgical approach can, in the long term, be considered a relatively harmless method.

Adult↗